This invention relates to a convertible road/rail power vehicle including a tractor unit provided with retractable wheel sets and rail equipment that enable it to be operated on either highways or railway tracks and when on rail to pull a multiplicity of loaded or unloaded railway cars.
The prior art has provided various forms of vehicles capable of being operated on either a highway or on a railway track. Vehicles which operate on both road and rail fall primarily into two main categories. In the first category are highway vehicles fitted with special rail dollies (two of which are known by the "Hy-Rail" and "HABCO" trademarks) which enable them to also operate on rail. The dollies, when lowered into operating position, take only that portion of the vehicle weight needed to provide adequate guidance. Sufficient weight is left on the vehicle's normal drive wheels to permit propulsion of the vehicle through its normal highway drive train. In this instance, the vehicles usually provide propulsion for their own movement only and do not pull any other vehicles. They are generally for rail service and maintenance operations which require vehicles for movement of material and personnel to and from work sites not reachable by road, as well as cranes and other service vehicles. Applicant is not presently aware of any in this category with the intended use of moving rail cars in revenue service.
The second category of vehicles which operate on rail and road includes those used for shunting rail cars at industrial plants and sidings. In this case, they are primarily designed for rail operation with the capability of providing high tractive effort for low speed shunting operations, but they are also fitted with retractable rubber wheel sets which permit them to operate on the ground in moving from one shunting operation to another. They are basically not designed or suitable for operation over highways at highway speed. Also, their capability of pulling strings of cars during shunting operations is not comparable to revenue train operation. While some do have brake systems that permit the application and release of train brakes, they do not have the sophisticated control necessary for mainline operation.